enable eslint for browser code

aws-node-auth0-custom-authorizers-api/frontend/app.js

@@ -1,4 +1,4 @@
-/* global window document localStorage fetch alert */
+/* eslint-env browser */
 
 // Fill in with your values
 const AUTH0_CLIENT_ID = 'your-auth0-client-id-here';

aws-node-single-page-app-via-cloudfront/app/app.js

@@ -1,31 +1,38 @@
-/* eslint-disable */
+/* eslint-env browser */
+/* eslint-disable no-var */
 
 // Renders the page based on the current URL
 function renderApp() {
   var content;
+  var main;
+
   if (window.location.pathname === '/about') {
-    content = '<div>Welcome to the About page</div>'
+    content = '<div>Welcome to the About page</div>';
   } else if (window.location.pathname === '/') {
-    content = '<div>Welcome Serverless Developer :)</div>'
+    content = '<div>Welcome Serverless Developer :)</div>';
   }
 
-  var main = document.getElementsByTagName('main')[0];
+  main = document.getElementsByTagName('main')[0];
   main.innerHTML = content;
 }
 
 // Navigate to another URL and re-render the application
 function navigate(evt) {
+  var href;
+
   evt.preventDefault();
-  var href = evt.target.getAttribute('href');
+  href = evt.target.getAttribute('href');
   window.history.pushState({}, undefined, href);
   renderApp();
 }
 
-document.addEventListener('DOMContentLoaded', function(event) {
+function render(/* event */) {
   // Attach the event listener once the DOM has been loaded
   var nav = document.getElementsByTagName('nav')[0];
-  nav.addEventListener("click", navigate, false);
+  nav.addEventListener('click', navigate, false);
 
   // First initial App rendering
   renderApp();
-});
+}
+
+document.addEventListener('DOMContentLoaded', render);